When the driver fails to respond to a request to intervene issued by a level 3 automated vehicle, the system considers a way to reduce the risk by performing a system operation called minimum risk maneuver (MRM). In this paper, a driving simulator experiment investigates the effects of MRM conditions such as hazard lamp activation, amount of deceleration, and stop position on vehicles approaching from the rear under different traffic conditions. As a result of the experiment, effective MRM conditions for reducing the risk of collision with a vehicle approaching from the rear are clarified, and we propose them as MRM considerations.